1. Field of the Invention
The present invention relates to the field of computing systems, and more particularly, microprocessor based systems, having improvements in energy conservation by decreasing the amount of electricity used or extending the battery life of a battery operated system. The invention also serves to reduce heat generation by reducing wasted energy which can allow greater system reliability and reduced requirements for air flow, fans, or other cooling methods.
2. Discussion of the Related Art
In this invention, the NAP refers to a short wait period during which power savings are achieved by reducing the number of system circuit elements that are clocked or that are clocked at full speed, since clock frequency is proportional to power consumption.
The NOP function commonly used in computer systems today derives its name from a no-operation function. This instruction allows the execution of a no-operation state in order to create a short time delay. Most microprocessor based systems today provide some type of NOP function which only serves to create a place holder in the processor instruction queue or to implement a fixed length short delay. In a typical microprocessor based system, the clock to the system remains fully active and the system power remains at peak levels during a NOP function.
In prior art systems, computers or microprocessor based systems have typically had to execute large numbers of NOPs or other types of dummy instructions to provide for delays of longer than one instruction cycle. One common problem with this type of methodology was that it suffered from large speed variations when the same programs were run on processors having different execution speeds.
In addition to a NOP function, another method commonly used to effect a wait period is to program a system timer or clock function to trigger an interrupt with an appropriate delay. However, this is substantially more complicated, requires additional system resources, and still requires that peak power be used needlessly.
Typically, power wasted in a system while in general use or during the execution of an operation intended specifically to do nothing has not been an issue as little or no consideration has previously been given to the power consumption of the system. With the desire for extended battery life in battery operated microprocessor based systems and energy conservation in AC electrically powered microprocessor based systems sponsored in part by environmental and economic concerns and the need to reduce heat generation in microprocessor based systems, the circuit according to the present invention overcomes the foregoing drawbacks of the conventional systems.